1. Field of the Invention
The present invention relates generally to fluid delivery devices. More particularly, the invention concerns an improved, dual reservoir apparatus for controllably mixing various medicinal agents and then delivering the agents into an ambulatory patient at specific rates over extended periods of time. One embodiment of the invention includes a novel adjustable flow rate control means for precisely controlling the rate of fluid flow from the reservoir of the device toward the patient.
2. Discussion of the Prior Art
Many medicinal agents require an intravenous route for administration of the medicament. The delivery device for delivering the medicament, while not an active pharmacologic agent, may enhance the activity of the drug by mediating its therapeutic effectiveness. Certain classes of new pharmacologic agents possess a very narrow range of therapeutic effectiveness, for instance, too small of a dose results in no effect, while too great of a dose results in a toxic reaction.
In the past, prolonged infusion of fluids has generally been accomplished using gravity flow methods, which typically involve the use of intravenous administration sets and the familiar bottle suspended above the patient. Such methods are cumbersome, imprecise and require bed confinement of the patient. Periodic monitoring of the apparatus by the nurse or doctor is required to detect malfunctions of the infusion apparatus. Devices from which liquid is expelled from a relatively thick-walled bladder by internal stresses within the distended bladder are well known in the prior art. Such bladder, or “balloon”-type, devices are described in U.S. Pat. No. 3,469,578, issued to Bierman and in U.S. Pat. No. 4,318,400, issued to Perry.
One of the most versatile and unique fluid delivery apparatus developed within recent years is that by one of the present inventors described in U.S. Pat. No. 5,205,820. The components of this novel fluid delivery apparatus generally include a base assembly, an elastomeric membrane serving as a stored energy means, fluid flow channels for filling and delivery, flow control means, a cover, and an ullage which comprises a part of the base assembly.
Another prior art patent issued to one of the present applicants, namely U.S. Pat. No. 5,743,879, discloses an injectable medicament dispenser for use in controllably dispensing fluid medicaments such as insulin, anti-infectives, analgesics, oncolylotics, cardiac drugs, biopharmaceuticals, and the like from a pre-filled container at a uniform rate. The dispenser, which is quite dissimilar in construction and operation from that of the present invention, includes a stored energy source in the form of a compressively deformable, polymeric, elastomeric member that provides the force necessary to controllably discharge the medicament from a pre-filled container, which is housed within the body of the device. After having been deformed, the polymeric, elastomeric member will return to its starting configuration in a highly predictable manner.
Another important prior art fluid delivery device is described in the U.S. Pat. No. 6,063,059 also issued to one of the present inventors. This device, while being of a completely different construction from the device of the present invention, embodies a compressible-expandable stored energy source somewhat similar to that used in the apparatus of the present invention.
As will be appreciated from the discussion which follows, the apparatus of the present invention is uniquely suited to provide precise, continuous fluid delivery management at a low cost in those cases where a variety of precise dosage schemes are of utmost importance. An important aspect of the apparatus of the present invention is the provision of dual reservoirs and novel means for filling the reservoirs with the same or different medicinal agents. One form of the invention includes a pair of rotatable fluid flow rate control means, each of which includes uniquely formed, multichannel flow rate control channels which enable precise control of the rate of fluid flow of the medicaments from either or both of the fluid reservoirs to the patient. More particularly, the apparatus of the present invention includes novel, adjustable fluid flow rate control mechanisms which enable the fluid contained within each of the fluid reservoirs of the device to be precisely dispensed to the patient at various selected rates. The apparatus also includes a reservoir selector means for selecting the reservoir from which the fluid will be removed and delivered to the patient via the flow rate control mechanisms.
Advantageously, the apparatus of the present invention can be used with minimal professional assistance in an alternate health care environment, such as the home. By way of example, devices of the invention can be comfortably and conveniently, removably affixed to the patient's body or clothing and can be used for the continuous infusion of antibiotics, such as, for example, an antibiotic sold by Abbott Laboratories under the name and style ANCIF and by Rosche under the name and style ROCEPHIN. The devices of the invention can also advantageously be used for the delivery of various analgesics such as morphine and like medicinal agents.
Additionally, the apparatus of the invention is useful in the mixing and delivery of various types of adjuvant drugs. Adjuvant therapy, which is additional treatment given after surgery, may include chemotherapy, radiation therapy, hormone therapy, or biological therapy. Adjuvant drugs are generally defined as auxiliary drugs used concurrently with nonopioid or opioid analgesics. Several types of adjuvant drugs play important roles in cancer pain management. Some, such as, laxatives, antiemetics, antinausea drugs, and stimulants, treat symptoms, such as constipation, vomiting, nausea, and sedation that may contribute to pain or develop as a side effect of therapy. Other adjuvant drugs enhance the pain-relieving effects of opioids, or independently provide relief for certain types of pain. Anticonvulsants, for example, can be used with opioids and are prescribed to treat neuropathic pain, especially pain that has an electric shock-like nature. Antidepressants, which are also coanalgesics for opioids, are prescribed for neuropathic pain that is experienced as a hot, burning sensation. Some other commonly prescribed adjuvants are antihistamines, anxiolytics, corticosteroids, local anesthetics and stimulants. Some of the more commonly used adjuvant analgesics include corticosteroids, nonsteriodal anti-inflammatory drugs, tricyclic antidepressants, anticonvulsants and bisphosphonates.
Thromboembolic disease may, by way of example, be treated by chemohormonal therapy using cyclophosphamide, methotrexate, fluorouracil, vincristine, prednisone, doxorubicin and tamoxifen.
The apparatus of the invention is also particularly useful in polychemotherapy which is defined as the use of more than one chemotherapy drug. Such treatment is generally considered to be substantially more effective than using a single agent. Giving more than one medication increases the odds of destroying all the cancer cells and the development of this strategy has accounted for major advances in cancer treatment. Tumors in their early stages grow rapidly because they have a high growth fraction. Over a period of time, as the number of cancer cells grows and the tumor burden increases, the tumor's growth fraction begins to decrease. Cell-cycle specific and cell-cycle non-specific drugs are given in combination, because the cell-cycle specific drugs reduce the tumor growth factor, and cell-cycle non-specific drugs help to reduce the tumor burden. Combination chemotherapy is typically given in courses or cycles. The number of courses varies depending on the type of cancer, the cytotoxic drugs used, and the patient's response to therapy. Combination therapy protocols are usually described by abbreviations that use the first letter of each drug in the protocol. For example, CAF (Cyclophosphamide+Adriamycin+Fluorouracil) is a combination protocol used to treat breast cancer.
There are several advantages of using a combination of drugs rather than a single agent. For example, combining drugs that act in different phases of the cell-cycle increases the number of cells exposed to cytotoxic effects. Similarly, combining drugs decreases the incidence and severity of side effects of therapy and decreases the possibility of drug resistance. Further, combinations of drugs are often effective in patients with large tumors containing a small number of cells that are reproducing. In this instance, one of the drugs kills a high proportion of tumor cells and stimulates the remaining tumor cells to start reproducing. The other drugs in combination therapy can then attack newly reproducing cells.
By way of summary, the apparatus of the present invention uniquely overcomes the drawbacks of the prior art by providing a novel, disposable dispenser of simple, but highly reliable construction. A particularly important aspect of the apparatus of the present invention resides in the provision of novel, self-contained energy sources which are in the form of expandable-retractable spring members that provide the force necessary to selectively and substantially uniformly dispense various solutions from the dual reservoirs of the device. Because of the simplicity of construction of the apparatus of the invention and the straightforward nature and operational reliability of the energy sources, the apparatus can be manufactured and maintained at low cost without in any way sacrificing accuracy and reliability.